Learned the hard way that a $75 deposit does not lock in your pickup date

I booked a carrier to move my Civic from Denver to Austin back in March and paid a $75 deposit to hold a pickup window of May 6th through the 8th. The dispatcher kept saying "you're locked in" but when May 7th came and went with no truck, I called and got a totally different story. Turns out that deposit only reserves you a spot in the queue, not an actual truck, which I wish someone had told me up front. I waited 11 extra days and the car finally got picked up on the 19th, and I paid $150 more than the quoted $875 because rates jumped. The thing that bugs me is how normal this seems to be, since two other companies said the same thing when I called around after. Is there any way to tell if a carrier actually has a truck assigned before you hand over money, or is this just how it works?